1. Field of the Invention
The present invention relates generally to printing presses and more particularly to a device and method for driving folding rolls in a folder.
2. Background Information
Web printing presses print a continuous web of material, such as paper. In a folder of the printing press, the continuous web then is cut into signatures in a cutting unit and folded.
One way to fold the resulting signatures is using a rotary blade folder, which includes a cylinder with rotary blades which provide a fold to the signature. The fold is forced by the blade toward two rotating folding rolls, which grip the signature along the fold at a nip, set the fold and deliver the folded product, for example, to a fan unit. Each of the folding rolls must be driven.
As shown in FIG. 4 herein, in a prior art rotary blade folder the drives for the interacting folding rolls include drive-in gears 1, 2 and roll gears 3, 4. The two drive-in gears 1, 2 interact in a geared 1:1 relationship, and each of the drive-in gears 1, 2 independently drives a roll gear 3, 4 respectively, gears 3 and 4 being coaxial with a respective folding roll. The coaxial gears 3, 4 and the folding rolls are adjustable about centers of gears 1, 2 as shown by arrows 5, 6, so that a nip between the folding rolls can be adjusted, for example to accommodate different printed product thicknesses. A seal or cover 8, shown schematically, generally surrounds all four of the gears of the folder drive, i.e. the two drive-in gears 1,2 and the two coaxial gears 3,4. The seal 8 helps provide for proper lubrication of the gears. However, because the two coaxial gears 3, 4 need to be moved during adjustment of a nip between the folding rolls, the seal 8 typically suffers flexing at location 7, which can lead to breakdown of the seal and/or leakage of lubricating oil.
An object of the present invention is to provide for a device and method for providing improved sealing for gears of a folder drive. An additional or alternative object of the present invention is to provide a high quality folder drive and related method.
The present invention provides a drive for two interacting folding rolls, the drive including a first drive-in gear, a first roll gear driven by the first drive-in gear, a first cover for sealing the first drive-in gear and the first roll gear, a second drive-in gear, a second roll gear driven by the second drive-in gear and adjustable with respect to the first roll gear, and a second cover for sealing the second drive-in gear and the second roll gear.
With the two-seal arrangement of the present invention, flexing or stressing of a seal can be avoided, even during nip adjustment when the first and second roll gears are moved.
The first and second roll gears preferably are coaxial to their respective folder rolls.
The first and second drive-in gears preferably are connected by a first axle and a second axle, respectively, to a first and second drive gears. First and second drive gears preferably intermesh. At least one of the first and second drive gears is connected to a drive motor.
The first and second axles preferably pass through a gear side wall of the folder, the drive-in gears being located inside the gear side wall and the drive gears being located outside the gear side wall.
One of the folding cylinders preferably is a rotary blade folding cylinder.
The first cover preferably is attached to a nip adjustment arm connected to one of the folding rolls, so as to move with the nip adjustment arm.
The present invention also provides a folder for a printing press including a first folding roll, a second folding roll interacting with the first folding roll for processing signatures, a first drive-in gear, a first roll gear connected to the first folding roll and being driven by the first drive-in gear and a first cover for sealing the first drive-in gear and the first roll gear. A second drive-in gear drives a second roll gear connected to the second folding roll, the second roll gear being adjustable with respect to the first roll gear. A second cover seals the second drive-in gear and the second roll gear.
The present invention also provides a method for sealing a drive of interacting first and second folding cylinders comprising the steps of:
sealing a first drive-in gear and a first cylinder gear of the first folding cylinder using a first cover, and
sealing a second drive-in gear and a second cylinder gear of the second folding cylinder using a second cover, the first cylinder gear being adjustable with respect to the second cylinder gear.